There are different types of forces that act in different
ways on structures such as bridges, chairs, buildings, in fact any
structure. The main examples of forces are shown below. Study the diagram
and text and then draw a diagram/pictogram to represent each of these
forces.

A Static Load : A good example of this
is a person seen on the left. He is holding a stack of books on his back but
he is not moving. The force downwards is STATIC.

A Dynamic Load : A good example of a
dynamic load is the person on the right. He is carrying a weight of books
but walking. The force is moving or DYNAMIC.

STATIC LOAD (standing
still)

DYNAMIC LOAD (moving)

Internal Resistance : The person
in the diagram is sat on the mono-bicycle and the air filled tyre is under
great pressure. The air pressure inside it pushes back against his/her
weight.

Tension : The rope is in “tension” as
the two people pull on it. This stretching puts the rope in tension.

INTERNAL RESISTANCE

TENSION

Compression : The weight lifter finds
that his body is compressed by the weights he is holding above his head.

Shear Force : A good example of shear
force is seen with a simple scissors. The two handles put force in different
directions on the pin that holds the two parts together. The force applied
to the pin is called shear force.

COMPRESSION

SHEAR FORCE

Torsion : The plastic ruler is twisted
between both hands. The ruler is said to be in a state of torsion.